The Internet Protocol (IP) Multimedia Subsystem (IMS) may be used for delivering IP multimedia services to a wireless transmit/receive unit (WTRU). Unsolicited Communication (UC) includes communication where the recipient does not want to receive the communication. UC may include SPAM over IP Telephony (SPIT) or Spam over IP Messaging (SPIM). UC may originate with a source within an IMS network, or it may originate from a source outside an IMS network.
Problems may exist with current UC prevention measures. For example, where a network operator manages UC contractually, it may be inexpensive to obtain new sender identities. The use of IMS may include added responsibility for operators and increased capital expenditure. Denial of service (DoS) prevention for the domain of time-critical communication may not be cost-efficient. Adaptive or random simulated behavior may mimic legitimate patterns well and management of the DoS prevention measures may become costly. Existing mitigation methods for DoS are network-centric, while UC, SIPT, and SPIM are receiver-centric. For example, an attacker may cause mayhem to a receiver without loading the network. It may be difficult for a network provider to protect customers from SPIT. Barring of communication based on automated reasoning of network entities, without involvement of a recipient, may give rise to regulatory and legal challenges.
Other UC attacks may be directed at the WTRU. Given the variety of platforms and systems which interact with each other, the large amount of reference values for trustworthy integrity attestation may make WTRU based attacks difficult to prevent. UC prevention measures, such as Consent Mailboxes (CMB), may be abused by SPITers by placing their spam messages on the CMB. For example, a SPITer may request to be added as a contact with the request message being spam, or may add a user of the target WTRU as a contact and may send the spam message in the welcome text.